Finding the closest point to a polygon in a shapefile using GeoPandas

Question

I have the following map of statistical regions of Belgium:

The blue dots correspond to coordinates for which I have temperature data. Surrounded by the red circle is Brussels. As it can be seen, there are no points inside Brussels and therefore I don't have temperature info for it.

I would like to assign the temperature in the closest blue point to Brussels. How could I find the closest point of the grid to the Brussels polygon using GeoPandas?

Answer 1

One of the solution would be like that:

import geopandas as gpd
points = gpd.read_file('/path/to/points.shp')
regions = gpd.read_file('/path/to/regions.shp')

# get Brussels' geometry by name
br_geom = regions[regions["name"]=="Brussels"].cascaded_union

# calculate distances between br_geom and the points
# {index: distance, index: distance, ...} / r[0]: index, r[1]: row in DataFrame
dist = {r[0]: r[1].geometry.distance(br_geom) for r in points.iterrows()}

# get the nearest point index
index = min(dist, key=dist.get)

#get the point by index
nearest_point = points.loc[index]

temp = nearest_point["temp"]
print(temp)

Sample data:

# points.shp

    id  temp    geometry
0   1   25.0    POINT (...
1   0   30.0    POINT (...
2   2   35.0    POINT (...

# regions.shp
    id  name      geometry
0   1   ...       POLYGON ((...
1   0   Brussels  POLYGON ((...
...
...